This application claims the priority of German application 198 28 254.0, filed Jun. 25, 1998 in Germany, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a sitting and/or lying arrangement, particularly a seat such as a vehicle seat or airplane seat of the type having a stable subframe comprising a seat frame of a seat part and a backrest frame of a backrest connected therewith, and having a base part which has a transversely stiff and longitudinally flexible construction,.
In the case of a known seat for vehicles or the like (German Patent Document DE 22 09 744 A1), the subframe has a forward, a rearward and two lateral frame parts, and a flexible or elastic base plate or bottom plate is connected to one or several of these frame parts, while it is separated from all the other parts of the frame and is connected with these by way of elastic elements, such as coil springs. In one embodiment of this seat, the elastic elements are constructed as corrugated and therefore correspondingly flexible sections of the bottom plate, so that a downward directed pressure admission as the result of the sitting person's weight causes a pressing-down of the two flexible sections and a deflection of the bottom plate in the downward direction. The cushion, which is made, for example, of foamed urethane rubber, is mounted on the frame, the frame and the cushion being covered by means of a casing made, for example, of vinyl leather.
Such a seat has the disadvantage that the cushion is too thick and will wear out after being subjected to a prolonged load. A proper resistance to the anatomic structure of the body required for a correct sitting is not ensured. One also does not sit in a two-point sitting position on the ischial tuberosities, which exist for this purpose, but slides onto the tip of the coccyx and sits in a so-called three-point sitting position, which is extremely uncomfortable. The result is the constant desire to change the body position in the seat, which, in the case of an automobile seat, may result in the lack of attention to traffic, a feeling of uneasiness and rapid fatigue as well as irritability. In the case of an airplane seat, this leads to a disturbing sitting sensation, pain in the area of the spinal column and to a lack of sleep during long flights so that the body cannot rest during the flight and considerable fatigue occurs at the destination. In the case of sick persons with, for example, neuropathic changes, such a three-point sitting position may result in a pressure sore; in the case of wounds of other origins, for example burns, it may result in wound healing impairments.
In the case of a known backrest with a backrest frame, a cushion and a back shell for a motor vehicle seat (German Patent Document DE 35 15 631 A1), a simple construction with a low installation depth is achieved in that the back shell covered toward the front by the cushion has an elastic transition area used for the fastening on the backrest frame and an elastic transition area which follows toward the flat center part, which transition area preferably has a profile which has a corrugated cross-section and permits a resilient movement of the center part perpendicularly to the main plane of the backrest.
In the case of a known sitting or lying arrangement of the initially mentioned type (German Patent Document DE 24 00 119 A1), the base part fastened by means of its forward and rearward end on the seat frame is a mat made of a resilient material which is essentially non-ductile per se, such as spring steel plate, which obtains its flexibility in the longitudinal direction by extensional corrugations which are made transversely to the longitudinal direction and at an equal distance from one another. The extensional corrugations have a V-shaped or U-shaped profile and are shaped in one piece out of the spring plate in such a manner that their V- or U-openings point upwards. When the mat is loaded by a sitting person, the opening width of the extensional corrugations is enlarged and therefore permits an extension of the mat in the longitudinal direction. Another mat is mounted in the backrest frame, in which case end edges of the mat extending in parallel to the extensional corrugations are fixed on the two vertically extending spans of the backrest frame.
It is an object of the invention to construct a sitting and/or lying arrangement of the initially mentioned type in the case of which the user's body is supported in an anatomically correct manner such that the body can relax and no pressure points occur.
According to the invention, this object is achieved by providing an arrangement of the above referred to general type, wherein the base part is formed of a thin corrugated spring plate whose corrugations extend transversely and spaced from one another in a longitudinal corrugation direction of the seat, and which is suspended by means of a forward end edge, which extends transversely, on a forward cross strut of the seat frame and is suspended by means of a rearward end edge, which extends transversely, on an upper transverse spar of the backrest frame, and wherein a cushion rests on the corrugated spring plate, which cushion is divided into a section forming a seat cushion and into a section forming a backrest cushion.
The sitting and/or lying arrangement according to the invention has the advantage that the base part made of a transversely stiff but longitudinally flexible material, such as spring steel, carbon fibers, glass fibers or kevlar fibers, titanium or the like, ensures an anatomically correct sitting with a hollow and therefore less stressed sacrococcygeal region and an axially stressed ischial tuberosity region, and simultaneously a base structure for the cushion adapting to the body is provided which, although it has a certain stiffness, can be continuously changed and adapted to the momentary sitting wishes; thus, for example, when a tired sitting person who is slumped forward slides to the front. The transversely stiff and longitudinally flexible base part will then adjust itself such that the ischial tuberosities axially load the base part. The cushion, which corresponds to the anatomical requirements and cushions the pressure isobars of the body during the sitting in different positions, is pulled onto this hard transversely stable but longitudinally flexible base structure. The longitudinally flexible but stiff base part can be placed into the cushion, can be suspended on the subframe, can be adjusted and/or can be sprung as a whole. By means of additional mechanisms, which are mounted on the suspension of the base part on the subframe, the arching can be adjusted in the area of the longitudinal flexibility and can be adapted to the momentarily desired sitting position. The cushion may consist of foam, of rubberized hair, of a breathing material, of a perforated silicone cover, of air chambers or the like. On the whole, the sitting and/or lying arrangement combines the positive characteristics of the anatomic seat design with the positive elements of the individual readjustability, in which case as little material as possible and as much material as necessary is used.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.